Peiella sedimenti gen. nov., sp. nov., a novel taxon within the family Caulobacteraceae isolated from sediment of a river.

A Gram-stain-negative bacterium, designated XZ-24T, was isolated from sediment of a river in Mianyang city, Sichuan province, PR China. Cells (1.0-2.0 µm long and 0.4-0.5 µm in width) were strictly aerobic, non-spore-forming, rod shaped, prosthecate and motile by means of a polar flagellum. Growth occurred at 10-37 °C (optimum, 30 °C), at pH 5.0-9.0 (optimum pH 7.0) and with 0-3.0 % (w/v) NaCl (optimum 1.0 % NaCl). The results of phylogenetic analysis based on genomes and 16S rRNA gene sequences indicated that XZ-24T formed a distinct phyletic branch within the family Caulobacteraceae and was most closely related to members of the genera Brevundimonas, Caulobacter and Phenylobacterium with 95.3-96.5 % 16S rRNA gene sequence similarities. The average amino acid identities (AAI) between XZ-24T and species of the family Caulobacteraceae were 47.0-64.5 %, which were below the genus boundary (70 %). The predominant cellular fatty acids were summed feature 8 (C18 : 1ω7c and/or C18 : 1ω6c), C16 : 0, C18 : 1ω7c 11-methyl and summed feature 3 (C16 : 1ω7c and/or C16 : 1ω6c), the isoprenoid quinone was Q-10, and the major polar lipids were 1,2-di-O-acyl-3-O-α-d-glucopyranuronosyl glycerol; 1,2-di-O-acyl-3-O-[d-glucopyranosyl-(1→4)-α-d glucopyranuronosyl] glycerol and phosphatidylglycerol. The genome size of XZ-24T was 2.64 Mb with a DNA G+C content of 68.9 %. On the basis of the evidence presented in this study, strain XZ-24T represents a novel species of a novel genus in the family Caulobacteraceae, for which the name Peiella sedimenti gen. nov., sp. nov. (Type strain XZ-24T=CCTCC AB 20 23 094T=KCTC 8038T) is proposed.

Phylogenomic and molecular markers based studies on clarifying the evolutionary relationships among Peptoniphilus species. Identification of several Genus-Level clades of Peptoniphilus species and transfer of some Peptoniphilus species to the genus Aedoeadaptatus.

To clarify the evolutionary relationships among Peptoniphilus species, whose members show association with increased risk for prostate cancer, detailed phylogenomic and comparative analyses were conducted on their genome sequences. In phylogenetic trees based on core genome proteins and 16S rRNA gene sequences, Peptoniphilus species formed eight distinct clades, with Aedoeadaptatus and Anaerosphaera species branching between them. The observed clades designated as Peptoniphilus sensu stricto (encompassing its type species), Harei, Lacrimalis, Duerdenii, Mikwangii, Stercorisuis, Catoniae and Aedoeadaptatus, show genus level divergence based on 16S rRNA similarity and average amino acid identity (AAI). The Genome Taxonomy Database also assigns most of these clades to distinct taxa. Several Peptoniphilus species (viz. P. coxii, P. ivorii, P. nemausensis and some non-validly published species) grouped reliably with the type species of Aedoeadaptatus (A. acetigenes) and are affiliated to this genus based on 16S rRNA similarity, AAI, and multiple uniquely shared molecular signatures. Hence, we are proposing the transfer of these species into the emended genus Aedoeadaptatus. Our analyses on protein sequences from Peptoniphilus genomes have also identified 54 novel molecular markers consisting of conserved signature indels (CSIs), which are specific for different Peptoniphilus species clades and provide reliable means for their demarcation in molecular terms. Lastly, we also show that based on the shared presence of these CSIs in the genomes of uncharacterized Peptoniphilus spp. (cultured and uncultured), their affiliations to the specific Peptoniphilus clades can be accurately predicted. These results should prove useful in understanding the potential involvement of Peptoniphilus-related species in diseases.

Profiling of the intestinal community of Clostridia: taxonomy and evolutionary analysis.

Aim: Clostridia are relevant commensals of the human gut due to their major presence and correlations to the host. In this study, we investigated intestinal Clostridia of 51 healthy subjects and reconstructed their taxonomy and phylogeny. The relatively small number of intestinal Clostridia allowed a systematic whole genome approach based on average amino acid identity (AAI) and core genome with the aim of revising the current classification into genera and determining evolutionary relationships. Methods: 51 healthy subjects' metagenomes were retrieved from public databases. After the dataset's validation through comparison with Human Microbiome Project (HMP) samples, the metagenomes were profiled using MetaPhlAn3 to identify the population ascribed to the class Clostridia. Intestinal Clostridia genomes were retrieved and subjected to AAI analysis and core genome identification. Phylogeny investigation was conducted with RAxML and Unweighted Pair Group Method with Arithmetic Mean (UPGMA) algorithms, and SplitsTree for split decomposition. Results: 225 out of 406 bacterial taxonomic units were ascribed to Bacillota [Firmicutes], among which 124 were assigned to the class Clostridia. 77 out of the 124 taxonomic units were referred to a species, altogether covering 87.7% of Clostridia abundance. According to the lowest AAI genus boundary set at 55%, 15 putative genera encompassing more than one species (G1 to G15) were identified, while 19 species did not cluster with any other one and each appeared to belong to a diverse genus. Phylogenetic investigations highlighted that most of the species clustered into three main evolutive clades. Conclusion: This study shed light on the species of Clostridia colonizing the gut of healthy adults and pinpointed several gaps in knowledge regarding the taxonomy and the phylogeny of Clostridia.

Alteromonas gilva sp. nov. and Erythrobacter fulvus sp. nov., isolated from a tidal mudflat.

Strains chi3T and sf7T were collected from a tidal mudflat around Dongmak beach in Ganghwa, Republic of Korea. Both strains were Gram-stain-negative, aerobic or facultatively anaerobic, and rod-shaped. Results of phylogenetic tree analysis based on 16S rRNA and whole-genome sequences suggested that strains chi3T and sf7T belong to the genera Alteromonas and Erythrobacter, respectively. The cells of strain chi3T were non-motile and grew at 15-45 °C (optimum, 38 °C), at pH 6.0-10.0 (optimum, pH 8.0) and in the presence of 0-9.0 % (w/v) NaCl (optimum, 2.0 %). The cells of strain sf7T were motile as they had flagella and grew at 20-48 °C (optimum, 38 °C), at pH 6.0-10.0 (optimum, pH 9.0) and in the presence of 0-5.0 % (w/v) NaCl (optimum, 1.0 %). Strains chi3T and sf7T have average nucleotide identity values (70.0-70.4% and 78.9-81.7 %) and digital DNA-DNA hybridization values (21.8-22.3% and 21.0-25.6 %) with reference strains in the genera Alteromonas and Erythrobacter, respectively. Data from digital DNA-DNA hybridization, as well as phylogenetic, biochemical and physiological analyses, indicated the distinction of the two strains from the genera Alteromonas and Erythrobacter, respectively, and we thus propose the names Alteromonas gilva sp. nov. (type strain chi3T=KACC 22866T=TBRC 16612T) and Erythrobacter fulvus sp. nov. (type strain sf7T=KACC 22865T=TBRC 16611T).

Holtiella tumoricola gen. nov. sp. nov., isolated from a human clinical sample.

The diversity of bacteria associated with biopsy material obtained from patients with colorectal cancer was investigated using culture techniques. A novel bacterium, strain CC70AT, was isolated by diluting a sample of homogenized tissue in anaerobic medium, and then plating to yield a pure culture. Strain CC70AT was a Gram-positive, strictly anaerobic, motile, rod-shaped bacterium. Formate, but not acetate, was a fermentative end-product from growth in peptone-yeast extract and peptone-yeast-glucose broth. The G+C content of DNA from strain CC70AT was 34.9 mol%. 16S rRNA gene sequence analysis revealed that the isolate was part of the phylum Bacillota. The closest described relatives of strain CC70AT were Cellulosilyticum lentocellum (93.3 %) and Cellulosilyticum ruminicola (93.3 and 91.9% sequence similarity across 16S rRNA gene, respectively). According to the data obtained in this work, strain CC70AT represents a novel bacterium belonging to a new genus for which the name Holtiella tumoricola gen. nov., sp. nov. is proposed. The type strain for our described novel species is CC70AT (=DSM 27931T= JCM 30568T).

Genome-based analyses of family Oxalobacteraceae reveal the taxonomic classification.

Family Oxalobacteraceae is known for the indicator of bacterial diversity in the environment and many of which are important beneficial bacteria. Previous studies on the taxonomic structure of family Oxalobacteraceae mostly relied on 16S rRNA gene analysis, or core-genome phylogeny of a limited number of species and resulted in taxonomic confusion within several genera. Developments in sequencing technologies have allowed more genome sequences to be obtained, enabling the revision of family Oxalobacteraceae. Here, we report a comprehensive analysis of phylogenomic trees, concatenated protein and up-to-date bacterial core gene phylogenetic trees, and genomic metrics for genus demarcation on 135 genomes of Oxalobacteraceae species to elucidate their interrelationships. Following this framework for classification of species in family Oxalobacteraceae, all the proposed genera formed monophyletic lineages in the phylogenomic trees and could also be clearly separated from others in the genomic similarity indexes of average amino acid identity, percentage of conserved proteins and core-proteome average amino acid identity.

Advanced prokaryotic systematics: the modern face of an ancient science.

Prokaryotic systematics is one of the most progressive disciplines that has embraced technological advances over the last century. The availability and affordability of new sequencing technologies and user-friendly software have revolutionised the discovery of novel prokaryotic taxa, including the identification and nomenclature of uncultivable microorganisms. These advances have enabled scientists to resolve the structure of complex heterogenous taxon and to rectify taxonomic status of misclassified strains due to errors associated with the sensitivity and/or reproducibility of phenotypic approaches. Time- and labour-intensive experimental characterisation of strains could be replaced with determining the presence or absence of genes or operons responsible for phenotypic and chemotaxonomic properties, such as the presence of mycolic acids and menaquinones. However, the quality of genomic data must be acceptable and phylogenomic threshold values for interspecies and supraspecies delineation should be carefully considered in combination of genome-based phylogeny for a reliable and robust classification. These technological developments have empowered prokaryotic systematists to reliably identify novel taxa with an understanding of community ecology and their biosynthetic and biodegradation potentials.

Reclassification of 11 Members of the Family Rhodobacteraceae at Genus and Species Levels and Proposal of Pseudogemmobacter hezensis sp. nov.

A novel Gram-stain-negative, aerobic, motile bacterial strain, D13-10-4-6T, was isolated from the bark sample of Populus × euramericana. The strain could grow at 15-35°C, at pH 6-10 and in 0-4% (w/v) NaCl, and the strain tested positive for oxidase and catalase activities. The main polar lipids were phosphatidylmonomethylethanolamine, diphosphatidylglycerol, phosphatidylglycerol, and phosphatidylethanolamine. The main respiratory quinone was Q-10, and the predominant fatty acid was C18:1 ω7c. The phylogenetic analyses showed that the strain belonged to the genus Pseudogemmobacter of the family Rhodobacteraceae. The family Rhodobacteraceae is an ecologically diverse group that includes bacteria from aquatic to terrestrial ecosystems. As a consequence, the classification of the family Rhodobacteraceae is difficult, not least when the early taxonomy work relied heavily on 16S rRNA gene analysis. Recently, the taxonomic status of many members of the family has been revised based on the genome analysis; however, there are still some classification conflicts due to the lack of genome sequences and parallel publication time. In this study, phylogenetic trees based on 16S rRNA gene, gyrB gene, and 120 concatenated proteins, the average amino acid identity (AAI) and percentage of conserved proteins (POCP) have been used for the analysis of strain D13-10-4-6T and other members of 15 genera within the family to further clarify their taxonomic relationships. For the data of phylogeny, AAI, and POCP, the taxonomic proposals are (1) reclassification of Rhodobacter tardus as the type species of a novel genus, Stagnihabitans gen. nov., as Stagnihabitans tardus comb. nov.; (2) reclassification of Tabrizicola alkalilacus, Tabrizicola sediminis, Tabrizicola algicola into a novel genus, Pseudotabrizicola gen. nov., as Pseudotabrizicola alkalilacus comb. nov., Pseudotabrizicola sediminis comb. nov., Pseudotabrizicola algicola comb. nov.; (3) reclassification of Rhodobacter sediminicola into the genus Cereibacter as Cereibacter sediminicola comb. nov.; (4) reclassification of Rhodobacter flagellatus, Rhodobacter thermarum, and Xinfangfangia soli into the genus Tabrizicola as Tabrizicola flagellatus comb. nov., Tabrizicola thermarum comb. Nov., and Tabrizicola soli comb. nov.; (5) reclassification of Xinfangfangia humi into the genus Pseudogemmobacter as Pseudogemmobacter humicola comb. nov.; (6) classification of strain D13-10-4-6T as a novel species of the genus Pseudogemmobacter, for which the name P. hezensis sp. nov. is proposed, the type strain is D13-10-4-6T (= CFCC 12033T = KCTC 82215T).

Penaeicolahalotolerans gen. nov., sp. nov., a novel bacterium of the family Cyclobacteriaceae isolated from a shrimp pond.

A Gram-stain-negative, non-motile, rod-shaped, aerobic bacterium (designated as LMIT005T) was isolated from shrimp ponds in Shantou, China. The new isolate was characterized taxonomically using a polyphasic approach. Based on 16S rRNA gene sequence analysis, strain LMIT005T was found to be affiliated with the family Cyclobacteriaceae of the order Cytophagales while appearing as a distinct lineage. The 16S rRNA gene sequence similarity between strain LMIT005T and Algoriphagus yeomjeoni KCTC 12309T, the closest type strain in the family, was 91.3 %. Strain LMIT005T grew optimally at 25 °C, pH 7 and in the presence of 2.0 % (w/v) NaCl. The DNA G+C content (data from genome sequence) was 40.5 mol%. Compared with reference strain A. yeomjeoni KCTC 12309T, the average nucleotide identity (ANI) of LMIT005T was 70 %. The sole respiratory quinone of LMIT005T was menaquinone (MK-7), and the major fatty acids were summed feature 3 (C16 : 1 ω6c / C16 : 1 ω7c). The polar lipids of strain LMIT005T were mainly composed of phosphatidylethanolamine, phosphatidylcholine, two unidentified amino lipids, two unidentified lipids, one unidentified glycolipid and one unidentified phospholipid. The draft genome of strain LMIT005T comprised 3 089 781 bp (3.09 Mb) nucleotides and 2773 genes. Antimicrobial resistant-related genes (blal, mexA, and mexb) were annotated in the genome of strain LMIT005T, which indicated that it might be able to resist ß-lactam antibiotics. This was further verified by antimicrobial resistant test. Given its distinct genomic, morphological, and physiological differences from previously described type strains, strain LMIT005T is proposed as a representative of a novel genus of the family Cyclobacteriaceae, with the name Penaeicola halotolerans gen. nov., sp. nov. The type strain is LMIT005T (=KCTC 82616T=CICC 25047T).

Phylotaxogenomics for the Reappraisal of the Genus Roseomonas With the Creation of Six New Genera.

The genus Roseomonas is a significant group of bacteria which is invariably of great clinical and ecological importance. Previous studies have shown that the genus Roseomonas is polyphyletic in nature. Our present study focused on generating a lucid understanding of the phylogenetic framework for the re-evaluation and reclassification of the genus Roseomonas. Phylogenetic studies based on the 16S rRNA gene and 92 concatenated genes suggested that the genus is heterogeneous, forming seven major groups. Existing Roseomonas species were subjected to an array of genomic, phenotypic, and chemotaxonomic analyses in order to resolve the heterogeneity. Genomic similarity indices (dDDH and ANI) indicated that the members were well-defined at the species level. The Percentage of Conserved Proteins (POCP) and the average Amino Acid Identity (AAI) values between the groups of the genus Roseomonas and other interspersing members of the family Acetobacteraceae were below 65 and 70%, respectively. The pan-genome evaluation depicted that the pan-genome was an open type and the members shared 958 core genes. This claim of reclassification was equally supported by the phenotypic and chemotaxonomic differences between the groups. Thus, in this study, we propose to re-evaluate and reclassify the genus Roseomonas and propose six novel genera as Pararoseomonas gen. nov., Falsiroseomonas gen. nov., Paeniroseomonas gen. nov., Plastoroseomonas gen. nov., Neoroseomonas gen. nov., and Pseudoroseomonas gen. nov.

Roseobacters in a Sea of Poly- and Paraphyly: Whole Genome-Based Taxonomy of the Family Rhodobacteraceae and the Proposal for the Split of the "Roseobacter Clade" Into a Novel Family, Roseobacteraceae fam. nov.

The family Rhodobacteraceae consists of alphaproteobacteria that are metabolically, phenotypically, and ecologically diverse. It includes the roseobacter clade, an informal designation, representing one of the most abundant groups of marine bacteria. The rapid pace of discovery of novel roseobacters in the last three decades meant that the best practice for taxonomic classification, a polyphasic approach utilizing phenotypic, genotypic, and phylogenetic characteristics, was not always followed. Early efforts for classification relied heavily on 16S rRNA gene sequence similarity and resulted in numerous taxonomic inconsistencies, with several poly- and paraphyletic genera within this family. Next-generation sequencing technologies have allowed whole-genome sequences to be obtained for most type strains, making a revision of their taxonomy possible. In this study, we performed whole-genome phylogenetic and genotypic analyses combined with a meta-analysis of phenotypic data to review taxonomic classifications of 331 type strains (under 119 genera) within the Rhodobacteraceae family. Representatives of the roseobacter clade not only have different environmental adaptions from other Rhodobacteraceae isolates but were also found to be distinct based on genomic, phylogenetic, and in silico-predicted phenotypic data. As such, we propose to move this group of bacteria into a new family, Roseobacteraceae fam. nov. In total, reclassifications resulted to 327 species and 128 genera, suggesting that misidentification is more problematic at the genus than species level. By resolving taxonomic inconsistencies of type strains within this family, we have established a set of coherent criteria based on whole-genome-based analyses that will help guide future taxonomic efforts and prevent the propagation of errors.

Genome based reclassification of Deinococcus swuensis as a heterotypic synonym of Deinococcus radiopugnans.

Deinococcus species are widely studied due to their utility in bioremediation of sites contaminated with radioactive elements. In the present study, we re-evaluated the taxonomic placement of two species of the genus Deinococcus namely D. swuensis DY59T and D. radiopugnans ATCC 19172T based on whole genome analyses. The 16S rRNA gene analysis revealed a 99.58% sequence similarity between this species pair that is above the recommended threshold value for species delineation. These two species also clustered together in both the 16S rRNA gene and core genome based phylogenies depicting their close relatedness. Furthermore, more than 98% of genes were shared between D. swuensis DY59T and D. radiopugnans ATCC 19172T. Interestingly, D. swuensis DY59T and D. radiopugnans ATCC 19172T shared high genome similarity in different genomic indices. They displayed an average nucleotide identity value of 97.63%, an average amino acid identity value of 97% and a digital DNA-DNA hybridization value equal to 79.50%, all of which are well above the cut-off for species delineation. Altogether, based on these evidences, D. swuensis DY59T and D. radiopugnans ATCC 19172T constitute a single species. Hence, as per the priority of publication, we propose that Deinococcus swuensis Lee et al. 2015 should be reclassified as a later heterotypic synonym of Deinococcus radiopugnans.

Proposal for reunification of the genus Raoultella with the genus Klebsiella and reclassification of Raoultella electrica as Klebsiella electrica comb. nov.

The order Enterobacterales was divided into seven families including the family Enterobacteriaceae in 2016. The genus Klebsiella within the family Enterobacteriaceae was divided into two genera Klebsiella and Raoultella in 2001. Here, our phylogenomic analysis shows that the genus Raoultella is nested within the genus Klebsiella. Klebsiella and Raoultella together are monophyletic and share average amino acid identities (AAIs) of 86.9-89.6% above the AAI threshold (86%) for genus delimitation within the family Enterobacteriaceae. Klebsiella and Raoultella share AAIs of 79.9%-85.0% with the other genera within the subfamily "Klebsiella clade", which are in the range of inter-genus AAIs (74-85%) within the family Enterobacteriaceae. Klebsiella and Raoultella also share six known conserved signature indels. Therefore, we propose to reunify Klebsiella and Raoultella to the single genus Klebsiella and reclassify Raoultella electrica as Klebsiella electrica comb. nov. Our genome-based taxonomic analyses also identified seven potential novel species within the unified genus Klebsiella.

Rouxiella aceris sp. nov., isolated from tree sap and the emended description of the genus Rouxiella.

Polyphasic taxonomic studies were performed for the seven strains, which were isolated from sap extracted from Acer pictum in Mt. Halla in Jeju, Republic of Korea. Cells of all the isolates were Gram-reaction-negative, facultatively anaerobic, short rods and contained the major isoprenoid quinone of Q-8, the predominant fatty acids of C16:0 and C17:0 cyclo and the major polar lipids including phosphatidylethanolamine, phosphatidylglycerol and an unidentified aminophospholipid. The G + C contents of the genomic DNAs were 50.6-51.3%.The 16S rRNA gene-based phylogeny exhibited that the seven isolates formed two distinct sublines within the family Yersiniaceae. In the 92 core gene analysis, strain SAP-1T formed a subline at the base of radiation of the genus Rouxiella and its assignment to the genus Rouxiella was supported by high amino acid identity values (82.0-83.4%), albeit with sharing low 16S rRNA gene identities (96.0-96.9%). The average nucleotide identity and digital DNA-DNA hybridisation values together with phenotypic differences showed that strains SAP-1T, SAP-7, SAP-8 and SAP-13 belonged to a new species of the genus Rouxiella, while strains SAP-2, SAP-3 and SAP-27 were strains of Rouxiella silvae. On the basis of data obtained here, Rouxiella aceris sp. nov. (type strain, SAP-1T = KCTC 72599T = CCM 9078T) is proposed, with the emended description of the genus Rouxiella.

Elizabethkingia argenteiflava sp. nov., isolated from the pod of soybean, Glycine max.

Soybean pods, separated and enclosed from the outside environment, are considered a suitable place to find new microbes. A Gram-stain-negative, aerobic bacterium, bacterial strain (YB22T) was isolated from the pod of Glycine max (soybean) collected from a rural area in Republic of Korea and characterized by using polyphasic taxonomy. Cells of the strain were rod-shaped (approximately 0.4-0.6 µm wide and 4.0-5.0 µm long), non-flagellated and formed silver-yellow colonies. Cells grew at 25-35 °C (optimum, 28-30 °C), at pH 5.0-9.0 (optimum, pH 7.0) and with 0-2.0% NaCl (optimum, 0 % NaCl). 16S rRNA gene sequencing showed that strain YB22T was phylogenetically closest to the genus Elizabethkingia, and showed highest similarities to Elizabethkingia occulta G4070T (96.7 %), Elizabethkingia meningoseptica ATCC 13253T (96.7 %), Elizabethkingia miricola DSM 14571T (96.6 %), Elizabethkingia bruuniana G0146T (96.5 %), Elizabethkingia ursingii G4122T (96.4 %) and Elizabethkingia anophelis R26T (96.2 %). Average amino acid identity values between strain YB22T and other taxa in the genus Elizabethkingia were all above the threshold range of genus determination. Average nucleotide identity and digital DNA-DNA hybridization values between strain YB22T and other phylogenetic relatives were all found to be below the threshold range for species determination. The respiratory quinone of strain YB22T was menaquinone 6 (MK-6) and the predominant cellular fatty acids were iso-C15 : 0 (47.8 %) and iso-C17 : 0 3-OH (18.5 %). The major polar lipids were phosphatidylethanolamine, four unidentified aminolipids and three unidentified polar lipids. The phylogenetic analysis and physiological and biochemical data showed that strain YB22T should represent a novel species in the genus Elizabethkingia, for which the name Elizabethkingia argenteiflava sp. nov. is proposed. The type strain for this novel species is YB22T (=KCCM 43263T=JCM 32097T).

Introducing EzAAI: a pipeline for high throughput calculations of prokaryotic average amino acid identity.

The average amino acid identity (AAI) is an index of pairwise genomic relatedness, and multiple studies have proposed its application in prokaryotic taxonomy and related disciplines. AAI demonstrates better resolution in elucidating taxonomic structure beyond the species rank when compared with average nucleotide identity (ANI), which is a standard criterion in species delineation. However, an efficient and easy-to-use computational tool for AAI calculation in large-scale taxonomic studies is not yet available. Here, we introduce a bioinformatic pipeline, named EzAAI, which allows for rapid and accurate AAI calculation in prokaryote sequences. The EzAAI tool is based on the MMSeqs2 program and computes AAI values almost identical to those generated by the standard BLAST algorithm with significant improvements in the speed of these evaluations. Our pipeline also provides a function for hierarchical clustering to create dendrograms, which is an essential part of any taxonomic study. EzAAI is available for download as a standalone JAVA program at http://leb.snu.ac.kr/ezaai .

Candidatus Sulfurimonas marisnigri sp. nov. and Candidatus Sulfurimonas baltica sp. nov., thiotrophic manganese oxide reducing chemolithoautotrophs of the class Campylobacteria isolated from the pelagic redoxclines of the Black Sea and the Baltic Sea.

Species of the genus Sulfurimonas are reported and isolated from terrestrial habitats and marine sediments and water columns with steep redox gradients. Here we report on the isolation of strains SoZ1 and GD2 from the pelagic redoxcline of the Black Sea and the Baltic Sea, respectively. Both strains are gram-stain-negative and appear as short and slightly curved motile rods. The autecological preferences for growth of strain SoZ1 were 0-25°C (optimum 20°C), pH 6.5-9.0 (optimum pH 7.5-8.0) and salinity 10-40gL-1 (optimum 25gL-1). Preferences for growth of strain GD2 were 0-20°C (optimum 15°C), pH 7.0-8.0 (optimum pH 7.0-7.5) and salinity 5-40gL-1 (optimum 21gL-1). Strain SoZ1 grew chemolithoautotrophically, while strain GD2 also showed heterotrophic growth with short chained fatty acids as carbon source. Both species utilized hydrogen (H2), sulfide (H2S here taken as the sum of H2S, HS- and S2-), elemental sulfur (S0) and thiosulfate (S2O32-) as electron donors and nitrate (NO3-), oxygen (O2) and particulate manganese oxide (MnO2) as electron acceptors. Based on 16S rRNA gene sequence similarity, both strains cluster within the genus Sulfurimonas with Sulfurimonas gotlandica GD1T as the closest cultured relative species with a sequence similarity of 96.74% and 96.41% for strain SoZ1 and strain GD2, respectively. Strains SoZ1 and GD2 share a ribosomal 16S sequence similarity of 99.27% and were demarcated based on average nucleotide identity and average amino acid identity of the whole genome sequence. These calculations have been applied to the whole genus. We propose the names Candidatus Sulfurimonas marisnigri sp. nov. and Candidatus Sulfurimonas baltica sp. nov. for the thiotrophic manganese reducing culture isolates from the Black Sea and Baltic Sea, respectively.

Genome-based classification of Acidihalobacter prosperus F5 (=DSM 105917=JCM 32255) as Acidihalobacter yilgarnensis sp. nov.

The genus Acidihalobacter has three validated species, Acidihalobacter ferrooxydans, Acidihalobacter prosperus and Acidihalobacter aeolinanus, all of which were isolated from Vulcano island, Italy. They are obligately chemolithotrophic, aerobic, acidophilic and halophilic in nature and use either ferrous iron or reduced sulphur as electron donors. Recently, a novel strain was isolated from an acidic, saline drain in the Yilgarn region of Western Australia. Strain F5T has an absolute requirement for sodium chloride (>5 mM) and is osmophilic, growing in elevated concentrations (>1 M) of magnesium sulphate. A defining feature of its physiology is its ability to catalyse the oxidative dissolution of the most abundant copper mineral, chalcopyrite, suggesting a potential role in biomining. Originally categorized as a strain of A. prosperus, 16S rRNA gene phylogeny and multiprotein phylogenies derived from clusters of orthologous proteins (COGS) of ribosomal protein families and universal protein families unambiguously demonstrate that strain F5T forms a well-supported separate branch as a sister clade to A. prosperus and is clearly distinguishable from A. ferrooxydans DSM 14175T and A. aeolinanus DSM14174T. Results of comparisons between strain F5T and the other Acidihalobacter species, using genome-based average nucleotide identity, average amino acid identity, correlation indices of tetra-nucleotide signatures (Tetra) and genome-to-genome distance (digital DNA-DNA hybridization), support the contention that strain F5T represents a novel species of the genus Acidihalobacter. It is proposed that strain F5T should be formally reclassified as Acidihalobacter yilgarnenesis F5T (=DSM 105917T=JCM 32255T).

Halorubrum amylolyticum sp. nov., a novel halophilic archaeon isolated from a salt mine.

A pleomorphic and non-motile halophilic archaeon forming light-red pigmented colonies, strain ZC67T, was isolated from the Yuanyongjing Salt Mine, Yunnan, China. Based on similarity search and phylogenetic analysis of the 16S rRNA gene sequence, strain ZC67T belongs to the genus Halorubrum and is closely related to the species of Halorubrum (Hrr.) saccharovorum JCM 8865T, Hrr. persicum C49T, Hrr. halophilum B8T, Hrr. lipolyticum 9-3T, Hrr. salsamenti Y69T and Hrr. depositum Y78T with 16S rRNA gene sequence similarities of 99.0%, 98.7%, 98.5%, 98.4%, 98.1% and 97.7%, respectively. The values of average nucleotide identity (ANI) and average amino-acid identity (AAI) between strain ZC67T and its close relatives were less than 90.5% and 89.3%, respectively. In silico DNA-DNA hybridization (DDH) analysis showed that DNA-DNA relatedness between strain ZC67T and its relatives is less than 45%. Values of ANI, AAI and in silico DDH were clearly below the thresholds used for the delineation of a new species. The major polar lipids of strain ZC67T were similar to other neutrophilic members in the genus Halorubrum containing phosphatidylglycerol, phosphatidylglycerolphosphate methyl ester, phosphatidylglycerol sulfate and sulfated mannosyl-glucosyl-glycerol diether-1. The DNA G+C content was determined to be 66.3 mol% (based on the draft genome). Combined with other diagnostic characteristics, e.g. phenotypic and chemotaxonomic differences, strain ZC67T is concluded to represent a novel species in the genus Halorubrum, for which the name Halorubrum amylolyticum sp. nov. is proposed. The type strain is ZC67T (=CGMCC 1.15718T = JCM 31850T).

Revisiting the Taxonomic Status of the Biomedically and Industrially Important Genus Amycolatopsis, Using a Phylogenomic Approach.

Strains belonging to the genus Amycolatopsis are well known for the production of a number of important antimicrobials and other bioactive molecules. In this study, we have sequenced the genomes of five Amycolatopsis strains including Amycolatopsis circi DSM 45561T, Amycolatopsis palatopharyngis DSM 44832T and Amycolatopsis thermalba NRRL B-24845T. The genome sequences were analyzed with 52 other publically available Amycolatopsis genomes, representing 34 species, and 12 representatives from related genera including Saccharomonospora, Saccharopolyspora, Saccharothrix, Pseudonocardia and Thermobispora. Based on the core genome phylogeny, Amycolatopsis strains were subdivided into four major clades and several singletons. The genus Amycolatopsis is homogeneous with only three strains noted to group with other genera. Amycolatopsis halophila YIM93223T is quite distinct from other Amycolatopsis strains, both phylogenetically and taxonomically, and belongs to a distinct genus. In addition, Amycolatopsis palatopharyngis DSM 44832T and Amycolatopsis marina CGMCC4 3568T grouped in a clade with Saccharomonospora strains and showed similar taxogenomic differences to this genus as well as other Amycolatopsis strains. The study found a number of strains, particularly those identified as Amycolatopsis orientalis, whose incorrect identification could be resolved by taxogenomic analyses. Similarly, some unclassified strains could be assigned with species designations. The genome sequences of some strains that were independently sequenced by different laboratories were almost identical (99-100% average nucleotide and amino acid identities) consistent with them being the same strain, and confirming the reproducibility and robustness of genomic data. These analyses further demonstrate that whole genome sequencing can reliably resolve intra- and, inter-generic structures and should be incorporated into prokaryotic systematics.